Fault Location Algorithm Research Articles

Flock: Accurate Network Fault Localization at Scale

Inferring the root cause of failures among thousands of components in a data center network is challenging, especially for "gray" failures that are not reported directly by switches. Faults can be localized through end-to-end measurements, but past localization schemes are either too slow for large-scale networks or sacrifice accuracy. We describe Flock, a network fault localization algorithm and system that achieves both high accuracy and speed at datacenter scale. Flock uses a probabilistic graphical model (PGM) to achieve high accuracy, coupled with new techniques to dramatically accelerate inference in discrete-valued Bayesian PGMs. Large-scale simulations and experiments in a hardware testbed show Flock speeds up inference by >10000x compared to past PGM methods, and improves accuracy over the best previous datacenter fault localization approaches, reducing inference error by 1.19-11x on the same input telemetry, and by 1.2-55x after incorporating passive telemetry. We also prove Flock's inference is optimal in restricted settings.

Differential equation fault location algorithm with harmonic effects in power system

About 80% of faults in the power system distribution are earth faults. Studies to find effective methods to identify and locate faults in distribution networks are still relevant, in addition to the presence of harmonic signals that distort waves and create deviations in the power system that can cause many problems to the protection relay. This study focuses on a single line-to-ground (SLG) fault location algorithm in a power system distribution network based on fundamental frequency measured using the differential equation method. The developed algorithm considers the presence of harmonics components in the simulation network. In this study, several filters were tested to obtain the lowest fault location error to reduce the effect of harmonic components on the developed fault location algorithm. The network model is simulated using the alternate transients program (ATP)Draw simulation program. Several fault scenarios have been implemented during the simulation, such as fault resistance, fault distance, and fault inception angle. The final results show that the proposed algorithm can estimate the fault distance successfully with an acceptable fault location error. Based on the simulation results, the differential equation continuous wavelet technique (CWT) filter-based algorithm produced an accurate fault location result with a mean average error (MAE) of less than 5%.

A new algorithm for fault location in multi-end underground cables using traveling waves

<p>A quick, reliable, and accurate fault location approach is essential in underground power systems protection. Being the most optimistic research topic of electrical power systems, this article presents an optimized algorithm for fault location in multi-end underground cables using travelling waves. Existing algorithms based on wavelet theory have fewer reliability and accuracy issues that raise an error to the power systems in fault location. The proposed layout presents a multiterminal underground cables system where the entire system is segregated into several fault identification sections where this model identifies the faulty section and the faulty half. Voltage and current wave transient at the mid-point of each fault locator are taken into account to eliminate the time-synchronous error. Traveling waves models are modelled using Bewley diagrams. Detecting the first and second traveling wave transient at both ends of each cable keeps the system reliable. Extensive simulations are simulated using the alternative transient program (ATP) to discriminate, identify, and locate several faults, while the system can also validate the faults near the busbar. The model is developed in MATLAB, and the obtained results depict the proposed algorithm's higher accuracy in fault location.</p>

Switch Fault Detection and Localization for T-Type Converter

Over the past decade, multilevel converters have received considerable interest in medium voltage applications. A large number of active switches in a multilevel converter increases the probability of switch failure and decreases the reliability of the system. An open switch fault can lead to a malfunction of the whole system and should be diagnosed as soon as possible. In this paper, an open-switch fault diagnosis method for a five-level H-Bridge T-type converter is presented. The proposed fault detection method and the fault localization algorithm are based on the switching patterns and the converter output voltage level observation. This approach is capable to detect and localize an open circuit fault for all switches. First, it is validated by simulations in Matlab Simulink and Simscape toolbox environments. Experimental results are also presented and discussed to validate the simulation results.

A Practical Fault Location Algorithm With Increased Adaptability for Active Low Voltage Grids

Quick power restoration has always been one of the grid operators' major goals and could be facilitated by the application of automatized fault location methods. The need for such methods is particularly visible in the low voltage (LV) grids which have been overlooked until now. Hence, this paper presents a novel turnkey solution to the fault location problem in LV grids. The proposed algorithm takes advantage of the growing data availability and employs a machine learning (ML) model for the prediction of the faulted point. In order to ensure the applicability of the method all the steps of its implementation are analyzed. The study begins by addressing the algorithm's data collection requirements and proposing a smart storage strategy. It continues with the implementation of advanced data processing and minimization techniques, such as the feature selection, and addresses the generalizability limitations of ML–based algorithms by proposing a retraining scheme. Finally, the algorithm's performance during load changes and data contamination is studied. For the validation of the algorithm a modified version of the CIGRE European LV benchmark was simulated. The results verify the algorithm's robustness against the main influencing parameters and reveal low mean absolute errors throughout the tests; the default study case error was 0.5 m.

Three-Terminal Lines Fault Location Using Two Main Terminals Data in the Presence of Renewable Energy Sources

Penetration of renewable energy sources (RESs) in power systems is increased considerably and fault location algorithms face considerable problems with the presence of RESs. Also, the third terminal of three-terminal lines is expanded as a cost-effective solution to energize the remote areas of medium voltage (MV) systems, while its data may not be measured and easily available. In addition, in cases where this data is obtainable, due to the excessive harmonics of the inverter-based resources (IBRs) in that terminal, the measured data includes high error. Therefore, providing a method for fault location in three-terminal lines in the presence of RESs is challenging. This paper proposes an accurate method to identify the fault location on these lines incorporating RESs without requiring the third terminal data. Due to current transformers saturation and transient response of capacitive voltage transformers, the fault location based on the faulted phase data contains significant errors. The proposed method combines both the faulty and healthy phases data to improve the accuracy of fault location. Its performance is evaluated on a MV system for different scenarios including various fault resistances, locations and types, and third terminal integration of RESs. The obtained results confirm superiority of the proposed method.

Имитационное моделирование воздушных линий электропередачи напряжением 610 кВ для исследования алгоритмов определения места возникновения однофазных замыканий на землю

As part of evolution of single phase to earth faults protection methods and tools in 6–10 kV networks the development of simulation study methods of these networks and their components becomes relevant. A significant direction in this area is upgrading of sensors installed directly on the wires and electrical transmission towers. These sensors are installed in the conditions of an electromagnetic field acting on them and dynamically changes both in time and space, especially during emergency modes including single phase to earth faults. Application of modern software offers a challenge for complex simulation study of electromagnetic fields distribution at the location of the measuring transducers in continuously variable electromagnetic environment. The above-noted statement determines the relevance of the research goal, which is the development of a simulation study method of 6–10 kV overhead power lines, the model of which is designed to study existing and create new single phase to earth fault location algorithms and devices. To solve the tasks set the methods of simulation study of overhead transmission lines and corresponding medium voltage networks in PSCAD and COMSOL Multiphysics software have been used. The general concept of design of a 6–10 kV network and an overhead transmission line simulation model is formulated. The geometrical parameters of the section of the model of an overhead power transmission line to simulate electromagnetic transients are selected, considering the frequency dependence of the line parameters (inductance and active resistance). The proposed model of the overhead transmission line is verified, and recommendations for its application are given. The developed “inductive” component of the proposed overhead transmission line model allows to provide high accuracy of calculation of transient components of currents and voltages during single phase to earth faults. It makes possible to use this model for the development and research of single phase to earth fault location algorithms. The developed approach to simulation study of an overhead transmission line is the field of interest for further research, as it makes it possible to calculate the components of the electric field which are observed during single phase to earth faults.

Enhanced two-terminal impedance-based fault location using sequence values

<span lang="EN-US">Fault at transmission line system may lead to major impacts such as power quality problems and cascading failure in the grid system. Thus, it is very important to locate it fast so that suitable solution can be taken to ensure power system stability can be retained. The complexity of the transmission line however makes the fault point identification a challenging task. This paper proposes an enhanced fault detection and location method using positive and negative-sequence values of current and voltage, taken at both local and remote terminals. The fault detection is based on comparison between the total fault current with currents combination during the pre-fault time. While the fault location algorithm was developed using an impedance-based method and the estimated fault location was taken at two cycles after fault detection. Various fault types, fault resistances and fault locations have been tested in order to verify the performance of the proposed method. The developed algorithms have successfully detected all faults within high accuracy. Based on the obtained results, the estimated fault locations are not affected by fault resistance and line charging current. Furthermore, the proposed method able to detect fault location without the needs to know the fault type.</span>

Research on fault location algorithm of TPSS based on PSOA.

It is extremely important to research traction power supply system (TPSS) protection technology in order to ensure the safe operation of urban rail transit. A TPSS includes rails, return cables, rail potential limiting devices, one-way conducting devices, drainage cabinets, ballast beds, and tunnel structural reinforcements. In urban rail transit, on the basis of the dynamic characteristics of the TPSS, a fault location algorithm based on particle swarm optimization algorithm (PSOA) is developed. An evaluation of multi-point monitoring data is proposed based on fuzzy processing of the average value of polarization potential forward deviation and multi-attribute decision-making. Monitoring points and standard comparison threshold values are determined by the distribution law of stray currents. In conjunction with the actual project, the model is trained using field measured data. Based on the results, TPSSOA is able to achieve optimal discharge current control, reduce network losses and improve power quality. Moreover, the reconstruction results demonstrate the high usability of the proposed method, which will provide guidance to design the TPSS in the future.

Phase Selection and Location Method of Generator Stator Winding Ground Fault Based on BP Neural Network

The phase selection and fault location methods of generator stator winding single-phase grounding fault are greatly affected by the transition resistance. A new phase selection and generator stator ground fault location approach based on the BP neural network is proposed in this research from a data-driven angle. This method uses a neural network to calculate the probability of three-phase fault occurrence to identify the fault phase and directly calculate the fault location that takes the amplitude and phase angle characteristics of zero-sequence voltage as input. The simulation results show that the stator ground fault phase selection and location algorithm based on the neural network can achieve correct phase selection and small positioning error, which has verified the effectiveness of the method.

Current Sensor Fault Localization and Identification of PMSM Drives Using Difference Operator

The permanent magnet synchronous motor (PMSM) has received increasing attention in traction applications. For those closed-loop control systems, the current sensor is one of the most sensitive components, which determines the control performance and safety operation. Therefore, the fault diagnosis of current sensors is of great importance to realize fault tolerance and further maintenance. In this work, a novel fault localization and identification method of the current sensor is proposed for PMSM drives. The residual between the measured current and estimated currents based on a modified <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha \beta $ </tex-math></inline-formula> reference frame is employed for the fault sensors’ localization. Besides, a second-order difference operator is adopted to identify the fault types. Moreover, a function is defined for preventing misdiagnosis, thus enhancing the algorithm’s robustness. The algorithm for the fault type identification would not be affected by the variation of motor parameters, granting it high flexibility to combine with not only the fault location algorithm in this article but also with other model-based methods. The effectiveness of the proposed approach is experimentally validated on an 11-kW platform of the PMSM fed by a three-level T-type inverter.

Principle and Verification of an Improved Algorithm for Cable Fault Location Based on Complex Reflection Coefficient Spectrum

Diagnostic methods for fault location in cable insulation have become increasingly vital with the development of long-distance cables. This article presents an improved method for fault location based on the complex reflection coefficient spectrum (CRCS). First, a mathematical model for a long high-voltage cable line with consideration of a distribution-parameter circuit of cable joints is established in the frequency domain, and the CRCS of the cable with joints is analyzed. Next, based on the principle of frequency domain reflectometry (FDR), an algorithm in time-frequency conversion which uses the CRCS as the analysis spectrum is proposed. And the positioning sensitivity of the method is improved by implementing a data process adopting a Chebyshev window function which is controllable and reduces the sidelobe effect effectively. Furthermore, the improved method is evaluated by performing the simulations and two field verification tests. In a field test for a 5.1-km-long 110 kV cable, the multiple cable joints could be located effectively, and the relative error is between 0.14% and 1.49%. Then, the method was conducted for the positioning of a high-resistance fault and multiple joints on a 2.7-km-long 110 kV cable and the relative error is 0.37%. It is worth noting that the cross-bonding links of both cable tests were artificially replaced with temporary links straight across each joint. For the cross-bonded cable system, the test result shows that an obvious reflection is found at the cross-bonding point, which can reduce the reliability and accuracy of the present method.

A current-based algorithm for one-end fault location in series capacitor compensated double-circuit transmission lines

Fault location is essential in series capacitor compensated double-circuit transmission lines regarding their capacity in transferring large amounts of power. The main challenge in the fault location of these lines is the nonlinear behavior of the metal-oxide varistor (MOV) in protecting the series capacitor against overvoltage during faults. In this paper, considering the MOV model and zero-sequence mutual coupling impedance between the two circuits, a new algorithm is presented for the location of single-line-to-ground faults, using currents measured at one end of the line. In this algorithm, first, a fault location is obtained for each data window, and then the exact location is calculated using statistical techniques. The proposed algorithm is independent of the measured voltages, and as a result, no error in the voltage measurement affects its accuracy. In addition, needing no telecommunication channel to access the data of the remote substation leads to reliability increasing and cost reductions. Not requiring pre-fault data is another advantage of the algorithm. The results indicate that the algorithm is independent of fault location and resistance, fault occurrence time, load conditions, and compensation level. In addition, the fault location error in all scenarios is within the standard range.

A distance Protection/Fault location algorithm for Double-Circuit transmission lines with asymmetrical circuits during Cross-Country faults

The impedance-measuring elements and fault locators in distance relays suffer from measuring the correct fault impedance and fault location when facing cross-country faults (CCFs). During such atypical faults, this paper proposes a distance protection along with a fault location algorithm for double-circuit lines with asymmetrical circuits. This is fulfilled through instantaneous fault-branch currents innovatively derived from the line six-phase circuit model analysis on a time-domain basis. The currents derived lead to the relations that are mathematically linear combinations of designated vectors. This makes the possibility of establishing vector-input adaptive linear combiners (VI-ALC) in accordance with the relations derived. Being fed from the vectors of instantaneous measurements at the relaying side, the VI-ALCs with a distinctive capability of online training would swiftly give an accurate estimation of the fault distances during CCFs. The estimations are exploited in a logical procedure for both of the distance protection and fault location functions, taking account of different position status of the CCFs’ comprising LG faults. The proposed algorithm is feasibly implementable and is independent of the system configuration. It operates robustly in high-ground resistance and noisy conditions. Through extensive simulation studies in PSCAD/EMTDC, performance of the proposed algorithm would be investigated and verified in a variety of fault scenarios.

Fault Location Method of Multi-Terminal Transmission Line Based on Fault Branch Judgment Matrix

Aiming at the difficulty of fault location of multi-source transmission lines, this paper proposes a fault location method for multi-terminal transmission lines based on a fault branch judgment matrix. The fault traveling wave signal is decomposed by Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), and the IMFs sensitive components that can characterize the fault characteristics of the target signals are selected by constructing a correlation-rearrangement entropy function. The arrival time of fault signals at the endpoint has been accurately calibrated by combining them with the Teager Energy Operator (TEO). To eliminate the influence of wave velocity and fault time on the location results, this paper proposes a two-terminal location method based on the line mode component to improve the location accuracy. On this basis, combined with the fault branch judgment matrix, the accurate location of multi-terminal transmission line faults is realized. This method has been shown to have high accuracy in detecting traveling wave heads, accurately judging fault branches, and producing a small error in fault location results. Compared with the existing multi-terminal transmission line fault location algorithm, it has obvious advantages and meets the needs of actual working conditions.

A Non-Iterative Fault Location Algorithm for Transposed/Untransposed Transmission Line Immune to Unsynchronized Measurements

This paper presents an impedance-based non-iterative fault location algorithm for a two-terminal line considering unsynchronized measurements to account for the loss of Global Positioning System (GPS) signal. Based on the availability of pre-fault signals two algorithms are proposed, one using pre-fault data and the other without using pre-fault data. The algorithms are formulated by using fundamental frequency phasor based decoupled modal components of the measured signals at both ends of the line while considering distributed line model. Application of decoupled modal components with distributed model enhances the accuracy of the presented algorithms in both transposed and untransposed configuration of the line. The proposed algorithms have been tested and analyzed with different fault conditions simulated in EMTP-RV platform. Comparative analysis with existing methods is also presented to establish prominent features of the proposed methods. The algorithms have also been tested with practical data of Power Grid Corporation of India Limited (PGCIL) and the test result validates the accuracy of the developed fault location algorithms.

Setting Free Fault Location for Three-Terminal Hybrid Transmission Lines Connected With Conventional and Renewable Resources

Three-terminal hybrid transmission lines (TTHTLs) are attractive from both environmental and commercial view. Hybrid transmission lines are growing due to urbanization, connecting an industrial load and renewable integration. A TTHTL comprises sections of both overhead lines and underground/subsea cables or overhead lines with different X/R ratios. Faulted section identification (FSI) is key for defining the adaptive/selective auto-reclosing scheme and estimation of the fault location for TTHTLs. In this paper, FSI and fault location algorithms are proposed without using the parameters of any line section. Novelty of the methodology lies in a two-stage approach to the problem. In the first stage, series impedance parameters of all the sections are calculated using closed loop formulae. These parameters are then utilized in identifying the faulted section. In the second stage, the above calculated line section parameters and faulted section are used to estimate complete line parameters including shunt capacitance and subsequently the fault location. The advantage of the proposed method is that it does not require an initial guess of the line section parameters, is non-iterative in the first stage, and provides correct fault section identification for TTHTLs. These features make it suitable for designing the selective auto-reclosing protection scheme for the TTHTLs within traditional protection relaying hardware. More importantly, the series impedance parameters calculated in the first stage constitute good initialization values for the non-linear problem of estimating the complete line parameters. This results in better convergence of the algorithm and accurate parameter estimation. The developed solution is verified using the PSCAD/EMTDC simulations for TTHTLs connected with conventional and different inverter-based renewable resources. The performance of the proposed solution is compared with commercially available solutions, and it is found to be accurate. This solution is amenable for implementation in line differential protection relays without additional infrastructural changes.

Selection of fault selection jump identification algorithms for high-speed railway traction networks

High-speed railways have become a new business card for China. When power supply faults occur in the electrical traction network of high-speed railways, the practice of sacrificing selectivity to ensure the reliability of the relay protection system often occurs, and a more effective relay protection scheme must be adopted if the reliability and selectivity of the protection system are to be taken into account. Fast and accurate identification of fault types and their removal from the traction network is of great significance for the stable operation of railway power supply systems. Therefore, it is particularly important to identify and locate fault solutions. This paper analyses the commonly used fault identification and location algorithms, determines the fault signal processing principles for fully parallel AT lines, determines which algorithms are used to identify and locate faults, and helps to improve the fault detection efficiency of railway power lines.

A Generalized Fault Location Approach for Any Type of Power Network

This paper presents a generalized fault location algorithm that can locate faults for any type of power network configuration. It enhances previous work presented by the authors by reducing the estimation steps but keeping its robustness and redundancy against traveling wave attenuation by power transformers, bad data, voltage signal errors and the impact of Inverter Based Power Sources (IBPSs). This is accomplished by forming arrays containing the network parameters and time-of-arrivals (ToAs) for fault signals captured by Digital Fault Recorders (DFRs), which are used as inputs to the algorithm to compute the accurate fault localization. The IEEE 39-bus system is used to validate the algorithm under different fault conditions using Electromagnetic Transients Program and Matlab as simulation tools.

A multi-objective optimal PMU placement considering fault-location topological observability of lengthy lines: A case study in OMAN grid

Using PMU data, the fault location algorithm has gradually been trended in the literature. Besides the optimality of the algorithm, the fault location application should directly receive the data of the faulty line from the PMU devices to have the best performance; using state estimation to create the input data of fault location algorithm not only wastes the golden time, but it also decreases the reliability. Given, it is not possible to install PMU devices in all buses of the system, it is better to install them for the lengthy lines having the most probability of the failure. Although various approaches have been presented in the literature to solve optimal PMU placement (OPP), the fault location observability has less been considered in OPP formulation Accordingly, this paper considers a new index, named fault location observability (FLO), as a second objective function in its OPP formulation. Using this index, in addition to minimizing PMU installation cost, the number of lengthy lines being directly observable are also maximized. Using the ɛ-constraint method, the multi-objective problem has been solved several times as single-objective optimizations. Given the constraints and objective functions are linear, the work presents a mixed integer linear programming (MILP) formulation for the placement problem. Using the GAMS under CPLEX solver, the global optimal solutions of MILP model corresponding to the various ɛ-constraints yields to a Pareto optimal front. The simulation results, next, implements the proposed method on the IEEE 300 bus test system as well as the practical OMAN grid to prove the effectiveness of the proposed method.